Tape Drivers

Tape drivers should be tested by performing several archive and restore operations. The cpio(1) and tar(1) commands can be used for this purpose. Use the dd(1M) command to write an entire disk partition to tape. Next, read back the data, and write the data to another partition of the same size. Then compare the two copies. The mt(1) command can exercise most of the I/O controls that are specific to tape drivers. See the mtio(7I) man page. Try to use all the options. These three techniques can test the error-handling capabilities of tape drivers:

• Remove the tape and try various operations

• Write-protect the tape and try a write

• Turn off power in the middle of different operations

Tape drivers typically implement exclusive-access open(9E) calls. These open() calls can be tested by opening a device and then having a second process try to open the same device.